CVE-2024-27355Public exploitNetwork attack vector

CPU exhaustion via unbounded ASN.1 OID decoding

Published Mar 1, 2024 · Updated Aug 13, 2024

Denial of service in phpseclib before 1.0.23, 2.0.47, or 3.0.36 allows remote attackers to exhaust CPU via a crafted ASN.1 OID. ASN1::_decodeOID accepts arbitrarily long OID content and repeatedly decodes its base-128 subidentifiers without a length bound, consuming CPU. Exposure requires a consuming application to load an attacker-controlled certificate or other ASN.1 object; successful input can stall its PHP worker.

CVSS severity7.5
High
EPSS probability0.57%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in phpseclib before 1.0.23, 2.0.47, or 3.0.36 allows remote attackers to exhaust CPU via a crafted ASN.1 OID. ASN1::_decodeOID accepts arbitrarily long OID content and repeatedly decodes its base-128 subidentifiers without a length bound, consuming CPU. Exposure requires a consuming application to load an attacker-controlled certificate or other ASN.1 object; successful input can stall its PHP worker.

The record

CVE
CVE-2024-27355
Published
Mar 1, 2024
Updated
Aug 13, 2024
Vendor
phpseclib
Product
phpseclib
Classifications
CWE-400, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 1, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 13, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.0 <1.0.23
  2. Affected versionversion=2.0 <2.0.47
  3. Affected versionversion=3.0 <3.0.36

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

phpseclib · phpseclibversion=1.0 <1.0.23; version=2.0 <2.0.47; version=3.0 <3.0.36

Published CVSS scores

7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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